1. Field of the Invention
The present invention relates to manual input devices also called mechanical switches, and particularly to feeling providing means which can provide a knob with a plurality of operation feeling (tactile sensation or force feedback) modes.
2. Description of Related Art
Conventionally a manual input device which has a knob and a position sensor for detecting the amount and direction of manipulation of the knob has been well known. Generally, this type of manual input device has feeling providing means for giving the knob the required kinesthetic force or clicking sensation so that the knob can be adequately manipulated with a satisfactory operation feeling.
FIGS. 17A and 17B show one example of a conventional manual input device of this type. In this case, it is a rotary manual input device; as clearly illustrated in the figures, it is mainly composed of a housing 101; a rotary shaft 102 which is rotatably supported by the housing 101 with one end of it protruding out through an opening 101a made in the housing 101; a knob 103 which is fixed to one end of the rotary shaft 102 protruding from the housing 101; feeling providing means 104 housed in the housing 101; and a position sensor 105. The feeling providing means 104 comprises a disc 107, fixed to the rotary shaft 102, with a prescribed arrangement of many dents 106 for a feeling pattern on its circumferential surface; and a ball 109 which is held pushed in one direction by an elastic body 108 and in contact with the circumferential surface of the disk 107. The position sensor 105 consists of a code-disc 110 fixed to the rotary shaft 102 and a photo-interrupter 111 with a light emitting element 111a and a light detecting element 111b facing each other on the front and back sides of the code-disc 110, respectively.
In this manual input device, as the knob 103 is rotated around the axis of the rotary shaft 102, the rotary shaft 102, disc 107 and code-disc 110 rotate in the same direction by the same amount as the knob 103. As the disc 107 rotates, the ball 109 held pushed in one direction by the elastic body 108 disengages from a dent 106 on the circumferential surface of the disc 107, slides up onto the land (portion with no dents 106), then engages with a neighboring dent 106. This cycle is repeated depending on the amount of rotation of the knob 103 and a change in the manipulation force is conveyed to the knob 103 as a clicking sensation. As the code-disc 110 rotates, slits 110a made in the code-disc 110 cross the set point for the light emitting element 111a and light detecting element 111b; the number of slits 110a which have crossed it and their direction are detected by the photo-interrupter 111 to get positional signals such as those for the amount and direction of rotation of the knob 103.
This type of manual input device is usually installed in a car-mounted apparatus controller provided in a car and used to control the functions of various car-mounted electric apparatuses such as an air conditioner, radio, TV, CD player and navigation system.
Such a car-mounted apparatus controller integrates the following mechanisms: a selection switch for selecting an electric apparatus to be controlled; a function selection switch for selecting one of various functions of the electric apparatus selected by the selection switch; and a manual input device for controlling the function selected by the function selection switch. Here, a knob as part of the manual input device is manipulated in order to control the various functions of each electric apparatus. By using this car-mounted apparatus controller, a driver can control the various functions of each electric apparatus by means of the conveniently located electric apparatus selection switches, function selection switches and manual input device, so that he/she can control the functions of various electric apparatuses easily and adequately without his/her safe drive being interrupted.
However, since, as shown in FIG. 17 the conventional manual input device has only one row of dents 106 as a feeling pattern and only one ball 109 to engage with these dents 106, it is impossible to change the knob operation feeling as necessary. Therefore, if the conventional manual input device is applied to a car-mounted apparatus controller, the user only experiences the same operation feeling through the knob 103 when controlling, for example, the temperature of the air conditioner as when controlling its air flow rate. This tends to cause the user to fail to do functional control properly.